Hand manipulable motorized saw for cutting plaster casts



Dec. 27, 1949 E. J. KUPJACK 2,492,156

HAND MANIPULABLE MOTORIZED SAW FOR CUTTING PLASTER CASTS Filed July 29, 1946 2 Sheets-Sheet 1 Eugene. J. Kupjack Dec. 27, 1949 'E. J. KUPJ ACK HAND MANIPULABLE MOTORIZED SAW FOR CUTTING PLASTER CASTS '2 Shecs-Sheet 2 Filed July 29, 1946 A In B r, a

FigiZ Eugene J. Kupj a.ck

Patented Dec. 27, .1949

OFFICE HAND MANIPULABLE MOTORIZED SAW FOR CUTTING PLASTER- GASTS EugeneJ. Kupjack, United States Navy Application July 29, 1946, Serial No. 686,831 8 Claims.- (01. 30--166) (Grantedunder the act of March amended April 30, 1928'; 370 O.

This invention relates to plaster cast cutters and more particularly to a new and improved type of plaster cast cutter embodying a cutting unit, which may be made in two or more types, one an edge cutter unit and another a surface cutter unit. The edge cutter unit is equipped with a saw blade which is actuated in a straight line up and down motion. The surface cutting unit is equipped with a semi-circular saw which has a rocking motion induced in it. This cutting device is considered a definite aid in the removal of plaster casts and works equally well on both types of casts, padded and unpadded.

Heretofore there have been roposed numerous plaster cutting devices which have frequently been in the form of circularly rotating saws, chain saws, and cylindrical drill-like members, the latter being used to produce a cutting effect similar to that obtained by a milling cutter. These de-' vices have given unsatisfactory performances because of their slow operation and because the thread, fabric and padding frequently wind up with the cutting tool thus causing it to break or stop. In the practice prior to the present invention, if the above known devices are not employed, the usual method of cutting the plaster away with a knife has been resorted to. This is disagreeable to both patient and doctor alike because of the time consumed and the danger involved.

It. is therefore an object of this invention to provide a plaster cast cutting device includin a cutting unit which may be made in a plurality of types or modifications, one an edge cutter unit, and another a surface cutter unit, said cutting units having a reciprocating action and adapted to prevent breakage or stoppage as a result of the fabric and padding of the plaster bandage winding up upon the rotating tool, as occurs in the use of rotating cutting tools.-

Another object of this invention is to provide a safe, economical, and compact plaster cutting device which is readily adapted to the purpose of removing a plaster cast in a minimum amount of time and with a minimum amount of discomfort to the patient.

A further object of this invention is to provide a cutting device with a plurality of interchangeable cutting head units which are easily removed and which can be readily sterilized.

A still further object of this invention is to provide a cutting device which will readily permit the turning of sharp corners while cutting a cast.

Still another object of this invention is to provide a device which is easy to oil and which requires very little other maintenance.

A further object of this invention is to provide a-device-which may be used to cut a window in a cast thus enabling the treatment to be administered in a particular area.

A still further object of this invention is to pro- 3, 1883, as G. 757) vide a device which will cut a cast regardless of its condition, whether wet. or dry.

The foregoing and other objects and advantages will become apparent from the specifications and, drawings which follow, in which: Y

Fig. 1 represents a side elevational view of the cutting device embodying an edge cutter unit, partially in section;

Fig. 2 representsa front elevational view of the same partially in. section;

Fig. 3 is a section taken through the guide holding blocks and the lower portion. of the sleeve substantially on the line 3-3 as shown in Fig. 1;

Fig. 4 is a sectional detail view of a portion of the device;

Fig. 5 is a section taken across the saw guide in Fi 1;

Fig. 6 represents aside elevational view of the cutting device embodying a surface cutter unit, and a cutter housing partially in section;

Fig, '7 represents a front elevational v view of the.

substantially on line casing I!) receiving an electricmotor l2 which drives shaft II, which in turn transmitsmotion to drive gear [5 through reduction gears 18. I

The cutting unit or head l1, which inFig. 1 is an edge cutting-unit, for example, is fitted into chamber l3 of casing Ill through a laterally disposed opening provided by casing extension 7 l4,

and is secured in place by means of a thumb screw, l9. Drive gear l5. engages flygear 23 which rotates on stud pin24 screwed through bearing block or gear mount 22- and cutter sleeve It. A guide slot 26 at the top of the insert sleeve [6 and bearing block 22 straddles a ing lv which properly places and holds the unit during cutting operations. Very little maintenance is required and insert sleeve l6 preferably is beveled to facilitate the oiling ofmoving parts, and access for assembly or replacement of parts.

A holding block orcutter housing 25 is provided, whichis divided into portions 25a and 25b. 1

These halves are secured together by means of screws 56v and are secured below the bearing block;

or gear mount 22 and within sleeve I E by means of screws 26. A slot 29 is provided in block 25v and is adapted to receive a saw guide 2'! which is secured to block 25a. as by means of screws 28. At the lower end of saw guide 21 and at right angles thereto is preferably welded an oval prefe erably metal shoe 30. to which is attached a preferably plastic shoe 31 secured thereto asby means 1 p v This, plastic shoe insulates the of screws 32. v metal shoe and is adapted to shield the skin of 3 the patient from any possible heat which may be generated between the saw guide 21 and saw blade 33. This shoe also prevents the cold metal from chilling the patients skin when the cutter is first used.

Bearing block or gear mount 22 is secured to sleeve I6 by means of screws 34. A washer 51 desirably spaces fiygear 23 from gear mount 22. Flygear 23 is free to rotate and is held in place on the aforementioned stud pin 24 by means of a washer and screw 36. The washer 35 is counter-sunk and is secured in place by the flush head screw 36 which is tapped into and concentric with stud pin 24. The washer 35 serves as a spacer for connecting rod 31. Flygear 23 is joined to connecting rod 31 by means of drive pin 38 which fits through a hole in washer 35 and screws into the flygear 23 adjacent its periphery. Connecting rod 31 is secured to the drive pin 38 by means of a nut 39 screwed on the pin at its outer end and saw blade 33 is linked to the lower end of connecting rod 31 by means of a union block 43. The saw blade 33 is secured to the union block 43 by means of a rivet 4i and the connecting rod 31 in turn is pivotally secured thereto by means of a nut and bolt 42.

At the bottom edge of saw blade 33 is a knife edge 33a which is adapted to part and remove any cast material which may accumulate in slot 30a within the shoe 30 and plastic shoe 3I. The

teeth of the saw blade 33 are set at a relatively wide distance apart to make a path sufficiently wide in the cast material to permit the saw guide 21 to pass through.

In the operation of the device, the electric motor I2 drives shaft H which in turn transmits motion todrive gear I5 through reduction gears I8. Flygear 23 meshes with drive gear I5, and the connecting means attached to the periphery of the flygear 23 are given a reciprocating motion which is conveyed to the saw blade 33, motion of which is limited to a straight line by guide block 25. Plastic shoe 3I is placed between the flesh and the bandage of the patient, and as the device is moved forward, the plaster and padding is easily cut.

Referring to Figs. 6 and 7 it will be noticed that the aforementioned surface cutter unit there shown is interchangeable with the edge cutter unit as to fitting the drive gear I5 and the head casing extension I4, and in both instances the thumb screw I9 secures the particular cutting unit of the device. In addition, it will be noted that features such as the cutting sleeve I6, flygear 23, pin 24, washer 35, screw 36, pin 38, nut 39, and connecting rod 31 are the same in each of the cutting units.

Gear mount or bearing block 43, desirably half cylindrical in shape, and having a lateral projec-.

tion or foot portion 44 having a bore adapted to receive a bearing sleeve 45, is secured within sleeve I6 by the screws 34. A lower connecting rod 46 clevised at both ends is secured to connecting rod 31 at its top and to curved connecting rod 49 at its bottom, by means of pins 41 and nuts 48. The curved connecting rod 49 is secured to a curvilinear saw 50 by means of a pin 5!. The saw 50 rotates on a pin 52 housed within a saw housing 53, said housing providing a passage therethrough for movement of saw and curved connecting rod 49. The cutter housing 53 preferably comprises two castings, 53a and 531) which are held together by pin 54 and are secured within sleeve I6 by means of screws 55.

In operation, the flygear 23, as in the embodi- 4 ment of Figs. 1 and 2, is given a rotary motion by drive gear I5, and this rotary motion drives connecting rod 31, lower connecting rod 46, and curved connecting rod 49 which moves the curvilinear saw 50 in an angularly oscillating motion. To assist in handling the cast cutter a knob 58 is secured at the outside of the casing I0 opposite the extension I4, and also opposite the cutter 33 (or 50) The motor holding portion of the casing I0 projects at right angles to the extension I4 and in conjunction with the knob 58 affords means for manually holding, supporting, guiding and manipulating the cast cutter in any desired manner. With one hand engaging the motor holding portion of the casing Ill and the other engaging the knob 56, the cast cutter may be freely moved in any direction for cutting and disengaging a cast with minimum damage, injury or discomfort to the patient.

The device of the invention is adapted for cut ting thick casts as well as thin casts. Heavier or thick sections may be clefted out by means of the surface cutting unit, thus making it possible for the edge cutter unit to readily pass through.

It will be apparent that various modifications may be made in the structure and arrangement of parts without departing from the spirit of the invention, the scope of which is defined in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. A cutting device comprising in combination, a casing, a shaft mounted in said casing, means for driving said shaft, said casing providing a chamber and having a laterally disposed opening communicating with said chamber, a drive gear connected with said shaft and disposed in said chamber, a removable sleeve received in said casing opening and extending into said chamber at right angles to the shaft, means for securing said insert sleeve in said casing, reciprocating drive means comprising a connecting rod and a crank gear therefor mounted in said insert sleeve and the crank gear disposed on the sleeve for operative engagement with said drive gear when the sleeve is inserted into said chamber, and cutter means mounted at the lower end of said insert sleeve and operatively connected to said reciproeating drive means.

2. A cutting device comprising in combination, a casing, a shaft mounted in said casing means for driving said shaft, said casing providing a chamber and having a laterally disposed opening communicating with said chamber, a drive gear connected with said shaft and disposed in said chamber, a removable sleeve received in said casing opening and extending into said chamber, means for securing said insert sleeve in said casing, a gear mount received and secured within 7 the upper portion of the sleeve, a fiygear mounted 65 cured to said fiygear, cutter means connected to said connecting rod means, a housing for said cutter means received and secured in the lower portion of said sleeve, said cutter means being mounted for movement in said housing, said cutter housing having a passage therethrough, said passage receiving said cutter for movement therein imparted by said connecting rod means.

3. A cutting device comprising in combination,'

a casing, a shaft mounted in said casing, means for driving said shaft, said casing providing a chamber and having a laterally disposed opening communicating with said chamber, a drive gear connected with said shaft and disposed in said chamber, a removable sleeve received in said casing opening and extending into said chamber, means for securing said insert sleeve in said casing, a gear mount received and secured within the upper portion of said sleeve, a fiygear mounted on said gear mount and adapted to mesh with said drive gear, connecting rod means pivotally secured to said fiygear, cutter means connected to said connecting rod means, a housing for said cutter means received and secured in the lower portion of said sleeve, said cutter means being mounted for movement in said housing, said cutter housing being in two parts having longitudinally disposed adjacent surfaces recessed to provide a passage therebetween, said passage receiving said cutter for movement therein imparted by said connecting rod means.

4. A cutting device comprising in combination, a casing, a shaft mounted in said casing, means for driving said shaft, said casing providing a chamber and having a laterally disposed opening communicating with said chamber, said casing having an extension providing said laterally disposed opening, a drive gear connected with said shaft and disposed in said chamber, a removable insert sleeve received in said casing opening and extending in said chamber; a pin secured to said casing in said chamber, said insert sleeve having a notch at its upper end embracing said pin, a set screw in said casing extension engaging and holding said insert sleeve, said insert sleeve being beveled at its top portion, reciprocating drive means mounted in said insert sleeve and disposed in operative engagement with said drive gear, and cutter means mounted at the lower end of said insert sleeve and operatively connected to said reciprocating drive means.

5. A cutting device comprising in combination, a casing, a shaft mounted in said casing, means for driving said shaft, said casing providing a chamber and having a laterally disposed opening communicating with said chamber, a drive gear connected with said shaft and disposed in said chamber, a removable insert sleeve received in said casing opening and extending into said chamber, means for securin said insert sleeve in said casing, a gear mount received and secured within the upper portion of said insert sleeve, a pin secured to said gear mount, a fiygear rotatably mounted on said pin, said fiygear being retained on said pin by means of a washer and flush screw, said fiygear being adapted to mesh with said drive gear, connecting rod means pivotally secured to said fiygear, cutter means connected to said connecting rod means, a housing for said cutter means received and secured in the lower portion of said sleeve, said cutter means being mounted for movement in said housing,

said cutter housing having a passage there through, said passage receiving said cutter for movement therein imparted by said connecting rod means.

6. A plaster cast cutting device comprising in combination, a casing, a shaft mounted in said casing, means for driving said shaft, said casing providing a chamber and having a laterally disposed opening communicating with said chamber. a drive gear connected with said shaft and disposed in said chamber, a cutting head insertable in said chamber as a unit, means for securing said cutting head within said chamber, said cutting head comprising a sleeve, a gear mount within the sleeve, 2, fiygear mounted on said gear mount and adapted to mesh with the aforementioned drive gear, a cutter housing having a portion received in the lower end of said sleeve, a cutting tool in the form of a curvilinear saw pivotally mounted at the lower end of said cutter housing, connecting means secured to said flygear and to said cutting saw and adapted to impart a rocking motion to said curvilinear saw.

7. A plaster cast cutting device comprising in combination, a casing, a shaft mounted in said casing, means for driving said shaft, said casing providing a chamber and having a laterally disposed opening communicating with said chamber. a drive gear connected with said shaft and disposed in said chamber, a cutting head insertable as a unit in said casing opening and extending into said chamber, means for securing said cutting head within said chamber, said cutting head comprising a cylindrical sleeve, a gear mount within the sleeve substantially half cylindrical in shape and having a lateral projection at its lower end and having a bore therethrough, a fiygear mounted on said gear mount and adapted to mesh with the aforementioned drive gear, a cutter housing havin a portion received in the lower end of said sleeve, a cutting tool in the form of a curvilinear saw pivotally mounted at the lower end of said cutter housing, connecting means secured adjacent the periphery of said fiygear, said connecting means being in three separate portions, secured together to permit relative hinging motion, an upper portion being connected to said fiygear, a central portion passing through and guided in the bore of said lateral projection of said gear mount, and a lower portion being curved in shape and secured to said curvilinear saw adjacent to its periphery and imparting a rocking motion to said curvilinear saw.

8. A cutting device comprising in combination, a casing, a shaft mounted in said casing, means for driving said shaft, said casing providing a chamber and having a laterally disposed opening communicating with said chamber, a drive gear connected with said shaft and disposed in said chamber, a cutting head insertable in said chamber as a unit, means for securing said cutting head within said lateral opening, said cutting head comprising a cylindrical insert sleeve, a gear mount within said sleeve, a fiygear mounted on said gear mount and adapted to mesh with the aforementioned drive gear, a blade saw, drive means connecting said fiygear to said blade saw, a saw guide receiving said blade saw, a cylindrical slotted block in two parts secured within the lower portion of the aforementioned insert sleeve, said saw guide being accommodated within and extending downwardly from said block, said saw blade having a knife edge at its lower end, said saw guide having a laterally disposed shoe at its lower end, said shoe having a slot therein, said knife edge at bottom of said blade saw being adapted to remove any cast material that may accumulate in said foot slot.

EUGENE J. KUPJACK.

REFERENCES CITED UNITED STATES PATENTS Name Date Roberts Sept, 23, 1890 Number 

